Field of Invention
The invention relates to an axially split pump for conveying a fluid.
Background Information
Axially split pumps, which are also referred to as horizontally divided pumps, are pumps in which the housing is divided in parallel with the axis of the shaft and that has a bottom part and a cover. Both the bottom part, as well as the cover each have a flange which are placed on top of one another for a mounting of the pump and are then fixedly connected to one another, for example are screwed to one another.
Axially split pumps have been known for a long time and are produced in a variety of embodiments, typically as centrifugal pumps, for example as single flow or dual flow pumps and as single stage or multi-stage pumps. In this connection the impeller of the pump can be arranged between two bearings (between bearing pump). Also the field of application of these pumps is very wide, for example, they are used in the oil and gas industry or in the water industry or in the field of generation of energy. Frequently axially split pumps are configured for a high operating pressure or for large volume flows and are suitable for pumping over large geodetic heights, for the conveyance through water pipelines or oil pipelines or for the desalination of sea water by means of reverse osmosis.
Naturally, the seal between the bottom part and the cover of the housing along the two flanges is of great importance having regard to axially split pumps. In this connection the purpose is, on the one hand, to seal the inner space of the pump with respect to the environment and, on the other hand, to seal such pressure spaces in the internal space of the pump with respect to one another in which different pressures are present during the operating state such as is, for example, the case for multi-stage pumps.
For sealing between the bottom part and the cover it is known to insert a flat seal between the two flanges, in particular for applications with high pressure, such that the two flanges do not directly contact one another in the mounted state, but rather contact the flat seal at both sides. Such flat seals require a high pre-load, in particular also in order to achieve the required aerial pressing between the bottom part, the cover and the flat seal.
An alternative technology for sealing between the bottom part and the cover, as is, for example, also described in the WO-A-2014/083374, consists therein of mounting the flanges of the bottom part and the upper part directly on top of one another without a seal lying there between. The respective surfaces of the two flanges then form sealing surfaces that, in the mounted state, have direct contact with one another. Having regard to this solution an outer sealing groove is typically provided in the bottom part or in the cover or in the bottom part and in the cover, the outer sealing groove extending over the complete axial length of the pump and into which a string-like sealing element, for example, an O-ring-like sealing element is inserted. After insertion of the string-like sealing element into the sealing groove, the bottom part and the cover are fixedly screwed to one another such that the sealing surfaces of the two flanges are in direct contact with one another and the string-like sealing element is elastically deformed in the sealing groove in order to thus ensure a reliable seal.